Optical system for oscillographs



K. R. GE'ISER OPTICAL SYSTEM FOR OSCILLOGRAPHS Oct. 7, 1952 A Fi led ma 25, 1950 2 SHEETSSHEET l OOUC'O'C'.

Inventor: Kenneth 1Q. Geiseri.

H is At t omney 0d. 7, 1952 GESER I 2,613,127

OPTICAL-SYSTEM FOR OSCILLOGRAPHS Filed May 25, 1950 i a v 2 SHEETS-SHEET 2 LOCUS 0F BEST F 0OUSING.

' Locus 0F sown.

BEAM 1.946111.

7 Irwvencom Kehnebh 1Q. Geiser,

Hi8 Attorney.

Patented Oct. 7, 1952 "'KennethER. Geiserr' schenectadm'f Y., assign'or --to General Electric Company, a corporation of New Hawk tAmilieationvMayizs; 1950, Serial Nar -163397 ra e-aims. 1

; My jinvention relates ,to oscillog'ra'phs of ':..the

optical type which employ lightasi-theQreCOfd- Jiiterval of time. .Such. portrayalsiare commonly termed ,oscillograph fshot's' [.or ."shottype" .oscil-lograms,-- since only a brief sample v of L-theelecitric function or .e-transient is .recorded.

- iln'such,oscillographs Lproducing "ishottype -.oscillograms, various optical systems i have .heretofore commonlylbeen employed inIorderltolprotduce r3: .time base; sweep of lthe .recordingl' light tacross a tsuitable .light; sensitive member, such I as a fi-lmz-orsc'reen. "In onetsuch systemrthe light sensitive member itself' is physic'allyipro- -.pel1e,d atsa constant rate of speedalong one-axis ztpastia recording light beam which is-simultane- .ously defiectedalong a coordinatevaxis. I-Iow- 'ever, because of the inertia of theapparatus ,supporting and :propelling the light sensitive .member as wellas the necessity of eliminating sextraneous light, this-system does not1end-itr-y-selftto the production of z-atconstanthighspeed ltime base deflection. in another'optical system commonly employed, :a flat mirror is arranged toreceivetabeammf light deflectedvalong one axis, tsuch .-as horizontal, and is rocked about I its I own corresponding axis to redefiect .simul- :taneously vthis incident 1 light beam -.a-long sa coordinate axisand thereby: to provide a time basis upong-a suitably positioned recording light sen- -s-itive-screen-or 'film. However, in this latter :system it is necessary to formant-extremely narrow pencil-like lightbeam and the screen must be tcurvedwsoa thatthe distance from the-light source --to the screen :will: remain-constant. regardless of .rthe'ang-ular position of the rocking-.mirrortin order to enable a proper. focusing of thelight beam uponthe screen. I

I Accordingly, .-a principal object of y my; invention -is to .provide -a .fshot-t-type noscillograph having .a simple and ueconomicalioptical system capablevlof .providing a sharply (delineated Lhigh speed vtwo r dimensional portrayal of an electrical junction or transient .iupon a suitablellight sen- ;sitive memberisuch Lassa recording "film or.a viewingnscreen.

zAnotheriobject Jotmy invention istoiprovide at simple and'economicaLoptical time base de- Q flection Isyjstem for La shot-type oscillo'graph iiyhichlprobl'uces an extremely; linear vthigh speed 'I timjebase deflection-of a'beam or light.

IATfurthercbje'ct: or myiinvention is tojprovide (01; sic-#109) aniopiticalf systemf'ror i'a lshot-type'' oscillcgraph in ich itlieit'i'mefba'se Isweep;produi'zin'gmemilee'r i ozruricuons as. a light "focusingmember. .l'Ajstill Ifiirthrtobject; of my invention is "to 5 provide "an optical system "for an oscillograph capable offorcusin'g'a fio'od typewide beamiltlumination-system to produce a tracetoi fineidelili-neation upon 'a "fiat light sensitive] recording memberlor .yiewin'gi screen.

, A ist'illifur'therspecific object .of my invention vis Tito .provide "an ;oscillograi h optical system whichiproducesa "ffshot type oscillogram. along ta plane coincident with the flat plane 'of'lthe photosensitive ,material Lin the conventional ifilmipackl g Intgeneral, iimy improved ioscillogra'ph' optical systems-comprises allinesource or; light which is ,Jdefiected .in response tto the magnitudeiof 'an electric ;paramete'r along l'the .optical axis of :a ,concaveisurface cylindricalitlight' reflecting "and I tccusing member which, Tin L-turn, functions to -.-redefiect and 'focus .Ith'e .Z'diver'genti incident light has. a movingsspotsalongione .axis of a: suitable light :sensitive .recording ..or .viewing .member.

' 'lhe term ".nptical airis iasiherein employed re- ..--fers ,j to -.the axis of 7 this concave surface light reflecting and focusing member- -which is parallel fto the-iopticali plane passing through a focal. line loftthe: member. and-savcentrai axisithereof.

A coord-inateiaxistime baseQdflection-df the a recording JightUacross tthisi light sensitive. mem- Jeer isyzpnoduced by a 'coincident arcuate travlel {of -v thi-s v -ooncav.e surfiacei light reflecting and "fo- -';cusing member. TMeansvare preferably included ':to ..-restr ain v"this-time chase-"producing reflecting and focusingimem-beri iunderrsuitable i tension and :therebyt-to produce :a-irigh-v initial velocity of i this .foous-i ngs-vmember when it:is released .to travel g-through its arcuate spathf An ioverevoltage 4 .aswitchingesystem may-lalso be provided for .in-

: creasinga-utomaticallm'the; intensity-bf. the. light s source :d-uring tthe recording .-interval, and for extinguishing the light source whileithetconcave isrefiecting and :iocnsing number is being rreset am preparation; forianotherrrecording.

' i'fihe'rnovel:featureswhichflxbelieve to :bechariacteristic no'f smyiinvention are ,set vtorth with particularity inithe cap-pended t'cla-ims. ;My inv'ention iit'self, fihowe'ver; 1 together with further 1 objects and advantages thereof, :ca'mbestcbezundrstood by r'ference' to lxthe following cdes'cripti-on ta-ken imconneetion 'With the accompanying drawing in which Fig. 1 is a perspective dia- 'r'amniatic -view1 df a'n o tionsystem emaodymg 5 iny :-"-invention; -=and Fig; 2 -is -'a "schematic diathe vertical, in accordance with the magnitude of an electrical parameter suppliedto -the galvanometer. The incident light impinging upon the mirror 5 from the filament is reflected as a linear image which is parallel to the axis of oscillation of mirror 5 and which is deflected along an orthogonal axis, such as horizontal, by the oscillation of the mirror 5. Although I have illustrated, and preferably employ, a light image producing and deflecting means, it will be appreciated that, alternatively, a ribbon light beam producing and deflecting means may be employed. Such ribbon light beam producing and deflecting systems are well known in the art and need not be described here.

In order to focus the linear image reflected from mirror 5 as a point upon a light sensitive member 6, such as a film or viewing screen, as well as to provide a means for producing a time base sweep across the screen, a segment of a cylindrical concave mirror I is located to receive the light reflected from mirror 5 and, to

redeflect this light upon the screen 6. The concave surfaced cylindrical mirror i is located with its optical axis substantially parallel to the direction of deflection of the vertical image reflected from the mirror 5 and at an angle of inclination with respect to this incident light such that the image is redeflected and coincidently focused to a point upon the screen 5. When the concave mirror 1 is stationary, the deflection of the image caused by mirror 5 produces a corresponding movement of the focused spot along a focal line of the mirror I which constitutes one axis of the screen 6, such as the Y axis designated in Fig. 1.

In order to provide a two dimensionalportrayal of the deflection of this moving spot by reference to a time base sweep along a coordinate axis of the screen 6, such as the X axis designated in Fig. 1, I provide means for propelling the concave mirror I to travel along an arcuate path with a constantly changing angle of inclination relative to the light reflected from mirror 5. As will be more fully explained below with reference to the operation of this optical system, the

instantaneous position of the concave mirror 1 during its path of travel is such that constant beam length and sharp focusing of the redeflected light upon the light sensitive member 6 is achieved throughout its movement along its arcuate path.

The concave mirror I is supported by a frame 8 which is pivotally mounted at its lower end by means of a swivel rod 9,firmly secured to frame 8 but free to rotate within suitable sockets ID in a pair of upright supports it and 12 disposed on opposite sides of the frame 8. A high tension spring I3 is attached to the frame 8 and functions to propel the mirror I to describe a limited arc, with the swivel rod 9 as its axis of rotation.

In order to enable the mirror 1 to be propelled through its path of travel with a high initial,

velocity, a cooking lever I4 is arranged torestrain the frame 8 in an initial cocked position against the tension of spring I3. The cooking lever I 4 is fulcrumed on a suitable pivot l5 secured to the upright support H and rides under the tension of a spring member H on a cocking pin l6 fastened to the frame 8. When the frame '8 is rotated toward an upright position, the cocking pin [6 slides along the under surface of the lever I4 and is engaged within a recessed shoulder l8 of the lever arm 14. Rotation of the frame 8 may, of course, be accomplished by any suitable means such as a forked cocking shaft H! which is arranged to engage an arm 20 secured to frame 8 when the cocking shaft 19 is depressed.

The mirror frame 8 may be released from its cocked position by merely depressing on opposite end 2| of the lever arm M by such means as a release rod 22. Thereupon, the cooking pin l6 disengages the recessed shoulder 18 of lever arm 14 and the mirror framed is propelled through its path of rotation by the force'of spring I 3.

In order'to arrest the movement of the mirror frame 8 without excessive shock or rebound, a pair of damping platforms 23 and 23 are provided. These damping platforms 23 and 23' are journaled on a supporting rod 24 extending between the upright supports II and i2 respectively, and are biased by an internal spring (not shown) to aninitial position inclined to the initial striking surface of the frame 8. The detailed construction of these damping platforms 23 and 23' is described and claimed in a U. 8. Patent No. 2,557,720 granted June 19, 1951 to Michael Boehm andassigned to the same assignee as the 7 present invention.

A synchronized over-voltage switching system isalso provided to supply the lamp I with normal voltage when the mirror frame 8 is cooked immediately prior to recording, and automatically to increase the voltage supplied to the lamp i during the recording interval. This synchronized switching system also functions to extinguish the lamp during-the cocking period sothat'no return trace will appear upon the light sensitive screen 6 when the mirror I is rotated back to its-initial cocked position. Two switches are preferably employed to accomplish this synchronized switching system; one switch 25 being actuated by the movement of cooking shaft 19 and another switch '26 being actuated by themo'veme'nt of swivel rod 9. Switch '25 may bea simple double terminal switch which is opened when the control cocking rod 19 is depressed, while switch 26 is preferably a three-terminal cam-operated switch in which a central'contact' arm 27 makes contact to either of two other terminals 28 and 29 respectively. When the mirror frame is in the cocked position illustrated in Fig. l, the lamp I is energized at normal voltage through switches 26 and 25 by connection to one-half of asecondary winding 30 of a supply transformer 31. In this position, lever 21 of cam switch 28 engages terminal 23 to complete this circuit is thereby closed through switch 25 which supplies the entire voltage developed across the secondary winding 30 of transformer 31 to the lamp 1; .When the cooking shaft '19 is depressed to recockthe mirror frame 8, switch 25 is opened, disconnecting the entire series circuit supplying prising a line source of light, a concave cylindril cal mirror located to receive light from said line source and to reflect and focus the light to a focal point, means operative in response to an electric parameter for deflecting the light from said light source in a direction parallel to the optical axis of said mirror which lies in the optical plane thereof, thereby to move said focal pointalong a focal line of said mirror, means to propel said mirror to travel through an arcuate path in a direction parallel to the direction of the incident light emanating from said source to redeflect said focal line in a direction perpendicular to said focal line, and a flat light sensitive screen located to coincide with a substantially linear portion of the plane through which said focal line is deflected.

4. An optical system for an oscillograph comprising a line source of light, a light sensitive screen, a concave cylindrical mirror located to 8 prising a line source of light, a concave cylindrical mirror located to receive light from said line source and to reflect and focus the light to a focal point, means operative in response to receive light from said line source and to re- $1.

flect and focus the light as a spot upon said screen, means for deflecting the light from said light source in a direction parallel to the optical axis of said mirror which lies in the optical plane thereof, thereby to move the light spot rig.

reflected from said mirror along one axis of said screen, and means to propel said mirror to travel through a limited arcuate path in a direction parallel to the direction of the incident light emanating from said source and at a con-- angle increase whereby the light spot is re-dem flected at a substantially constant speed along said coordinate axis of said screen.

5. An optical system for an oscillograph comprising a line source of light, a light sensitive screen, a concave cylindrical mirror located to 5' receive light from said line source and to reflect and focus the light as a spot upon said screen, means for deflecting the light from said light source in a direction parallel to the optical axis of said mirror which lies in the optical plane thereof to move the light spot reflected from said mirror along one axis of said screen, means to propel said mirror to travel through a limited arcuate path in a direction parallel to the direction of the incident light emanating from said source to re-deflect the reflected and focused light spot along a coordinate axis of said screen, cocking means to restrain said mirror against a tensional force exerted by said propulsion means, and means to release said mirror from said cocking means to enablesaid mirror to be propelled under the force of said propulsion .means to move through said arcuate path with high initial velocity.

6. An optical system for an oscillograph coman electric parameter for deflecting the light from said light source in a direction parallel to the optical axis of said mirror which lies in the optical plane thereof, thereby to move said focal point along a focal line of said mirror constituting one focal axis thereof, and means to propel said mirror to travel through an arcuate path in a direction parallel to the direction of the incident light emanating from said source to re-deflect said focal line along a locus of points having substantially equal sums of focal radii and constituting a coordinate focal axis of said mirror, and means for supporting a flat light sensitive screen in the focal plane of a substantially linear portion of said coordinate focal axis.

7. An optical system for as oscillograph comprising a line source of li ht, a plane surface mirror adapted to be moved in response to the magnitude of an electric parameter and located to intercept and deflect the light from said line source along a predetermined axis, a light sensitive screen, a concave surfaced cylindrical mirror oriented with its optical axis substantially paral- 161 to said axis of deflection and located to intercept the light reflected from said plane surface mirror at a predetermined angle of incidence with respect thereto and to re-reflect and focus the incident light from said plane mirror at any instant throughout its range of deflection as alight spot at a corresponding point along one axis of said screen, and means to propel the concave mirror to travel along an arcuatepath intercepting the plane surfaced mirror reflected light with a continually changing angle of inclination, thereby to re-deflect the light spot along a coordinate axis of said screen While maintainingthe focusing thereof.

8. An optical system for an oscillograph comprising a line source of light, a plane surface mirror adapted to be moved in response to the magnitude of an electric parameter and located to intercept and deflect the image of said light source along a predetermined axis, a concave cylindrical mirror oriented with its optical axis substantially parallel to said axis of deflection and located to project and focus the incident light from said plane mirror as a light spot moving along a focal axis of said concave mirror in accordance with said plane mirror deflections of said light image, means to propel said concave mirror to travel along an arcuate path in a direction parallel to and intercepting said plane surfaced mirror reflected light simultaneously to re-deflect said light spot along a coordinate focal axis relative to said one focal axis, and light sensitive means located in the plane of both said focal axes to receive a delineation of said moving light spot.

9. An optical system for an oscillographlcomprising a line source of light, a plane surfaced mirror adapted to be moved in response to the magnitude of an electric parameter and located-to intercept and deflect the light from said line source along a predetermined axis, a concave cylindrical mirror oriented with the'optical axis which lies in its optical plane substantially parallel to said axis of deflection and located to project and focus the incident light from said plane mirror as a spot deflected along the focal line of said concave mirror, means to propel said concave mirror to travel along an arcuate path intercepting and in a direction parallel to said plane surfaced mirror reflected light to move said focal line through a locus of points constituting a coordinate axis of deflection, a series of said locus of points having equal sums of focal radii and lying within a substantially flat plane, and means for supporting a light sensitive screen in said flat plane portion of said coordinate axis of deflection.

10. An optical system for an oscillograph comprising a line source of light, a plane surface mirror adapted to be moved in response to an electric parameter and located to intercept and deflect the light from said line source along a predetermined axis, a light sensitive screen, a concave cylindrical surface mirror oriented with its optical axis substantially parallel to said axis of deflection and located to re-reflect and focus incident light received from said plane surfaced mirror as a spot along one axis of said screen, and means to propel said concave mirror to travel through a limited arcuate path in a direction parallel to said incident light to re-deflect said light spot along a coordinate axis of said screen, said concave mirror intercepting said incident light during its arcuate travel with a continually increasing angle of incidence but with a continually decreasing increment of incident angle increase for a constant angular velocity of said mirror, said mirror propulsion means being adapted to accelerate the velocity of said mirror during its arcuate travel to offset said decreasing increment of incident angle increase, and thereby to re-deflect the light spot at a substantially constant velocity along said coordinate axis of said screen.

11. An optical time base deflection system for an oscillograph comprising a line source of light, a light sensitive member, a concave cylindrical surfaced light reflecting and focusing member located to receive light from said line source and to project and focus the light as a spot upon said light sensitive member, and means to propel said light reflecting and focusing member to travel through an arcuate path in a direction parallel to the direction of the incident light from said light source to deflect said light spot.

along a time base axis of said light sensitive member.

'12. An optical time base deflection system for an oscillograph comprising a line source of light, a concave cylindrical mirror located to receive light from said line source and to focus the light to a focal point, means to propel said mirror to travel through an arcuate path in a direction parallel to the direction of incident light from said light source to deflect said focal point along a locus of points constituting an axis of deflection, and means for supporting a light sensitive member in the plane of said axis of deflection.

13. 'An optical time base deflection system for an oscillograph comprising a line source of light, a light sensitive screen, a concave cylindrical mirror located to receive light from said source I and to reflect and focus the light as a spot upon said screen, and means to propel said mirror to travel through a limited arcuate path in a direction parallel to the direction of incident light from said source to deflect the light spot along a time base axis of said screen, said mirror intercepting the incident light during its arcuate travel with a continually increasing angle of incidence but with a continually decreasing increment of incident angle increase, and said mirror propulsion means being constructed to accelerate the velocity of said mirror during its arcuate travel to compensate for said decreasing increment of incident angle increase, thereby to provide a substantially linear time base-deflection of said light spot along said screen.

14. An optical time base deflection system for an oscillograph comprising a source of light, a light sensitive screen, a mirror located to receive light from said light source and to reflect the light upon said screen, means to propel said mirror to travel through a limited arcuate path in a direction parallel to the direction of incident light from said light source to deflect the light along a time base axis of said screen, cocking means to restrain said mirror against a tensional force exerted by said propulsion means, and means to release said mirror from said cocking means to enable said mirror to be propelled under the force of said propulsion means to move through said arcuate path with high initial velocity.

15. An optical time base deflection system for an oscillograph comprising a source of light, a light sensitive screen, a mirror located to receive light from said light source and to reflect the light upon said screen, means to propel said mirror to travel through a limited arcuate path in a direction parallel to the direction of incident light from said light source to deflect the light along a time base axis of said screen, cocking means to restrain said mirror against a tensional force exerted by said propulsion means, means to release said mirror from said cocking means, and overvoltage supplying means connected to said light source and energized by the release of said mirror from said cock ng means to increase the voltage supplied to said light source during the period of said arcuate travel of said mirror.

KENNETH R. GEISER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,913,200 Hathaway June 6, 1933 2,269,674 Liddel et a1 Jan. 13, 1942 FOREIGN PATENTS Number Country 1 Date 259 Great Britain of 1912 

